Self-priming centrifugal pump



Oct. 4, 1966 A. s. MARLOW SELF-PRIMING CENTRIFUGAL PUMP 4 Sheets-Sheet 1 Filed Jan. 5, 1965 INVENTOR E W N w w R T A T M WA 8 5 DM H m R L 7 M A. S. MARLOW SELF-PRIMING CENTRIFUGAL PUMP Oct. 4, 1966 4 Sheets-$heet 2 Filed Jan. 5, 1965 FIGZ.

O d. 4, 1966 A. s. MARLOW 3,276,385

SELF-PRIMING CENTRIFUGAL PUMP Filed Jan. 5, 1965 4 Sheets-Sheet 5 INVENTOR ALFRED S. MARLOW H IS ATTORNEYS Oct. 4, 1966 A. s. MARLOW SELF-PRIMING CENTRIFUGAL PUMP 4 Sheets-Sheet Filed Jan. 5, 1965 i NVENTOR ALFRED S. MARLOW BY W.?u M M HlS ATTORNEYS United States Patent 3,276,385 SELF-PRIMING CENTRIFUGAL PUMP AlfredS. Marlow, Sharon, Conn. Filed Jan. 5,1965, Ser. No. 423,456 9' Claims. (Cl. 103-113) Thisinvention relates to improvements in pumps and more particularly to self-priming centrifugal pumps of simplified structure and manufacture.

Centrifugal pumps of the type heretofore available include a pump casing or housing having a scroll for receiving an impeller. In most cases, the scroll is cast integral with the pump housing. In the production of such pump housings or casings, it is necessary to use molds having central cores for the production of the hollows in the casting or castings and these cores are diflicult to make and position when the scroll forms an integral part of the pump casing or housing. Even when the scroll is a separate casting, internal cores are required to form the internal surfaces of the casing and the scroll to the desired shape and dimensions. The manufacture of the pump casings or housings is further made difficult by reason of the fact that surfaces of relatively large areas must be machined to relatively close tolerances to provide leak-tight-joints, even with gaskets, and considerable drilling and grinding is also required to enable the various component parts of the casing, scroll, impeller and associated structure to be assembled in proper relation. As a result, production rates of the prior centrifugal pumps are relatively low and the manufacturing costs are high. In addition, when the scroll is made an integral part of the pump casing or housing, it. must be provided with machined wear plates to avoid the need for replacement of the entire pump casing after prolonged use.

In accordance with the present invention, centrifugal pumps are provided which are composed of a plurality of parts which can easily be formed by simple coreless casting operations or by die casting so that the manufactu-re of the parts is simplified, their cost is greatly reduced and. manufacturing of the pumps are greatly facilitated.

More particularly, in accordance with the invention, the pump casing or housing is a two-part structure,.each part being formed by a simple casting operation and containing a scroll composed of separate, easily formed parts and readily assembled within the casing in proper relation to the impeller to provide efiicient pumping of a liquid and priming of the pump; Each of the parts of the 'pumphousing. and scroll, when-made in sand casting molds, requires only the grinding of relatively small surface portions thereof to insure proper fit and the drilling-of a minimum number. of holes therein for positioning and alignment of the parts. Surface finishing ofthe majorareas of the parts is unnecessary without loss .of efiiciency or appearance. of the pump andits component parts. Whendie cast parts are formed, even the grinding operations and drilling cant be. eliminated, thereby requiring only a few holes to be tapped for reception of locating and fastening elements and'pump connections.

For a better understanding of the present invention, reference may be had to the accompanying drawings, in which:

FIGURE 1 is a view partially in side elevation and partially in vertical section of a typical self-priming centrifugal pump embodying the present invention;

FIGURE 2 is an endelevational view ofthe pump;

FIGURE 3 is a view in section taken on line 33 of FIGUREJ;

FIGURE 4 is a view in section taken on line 44 of FIGURE 1;

FIGURE 5 is a front elevational view of a check valve gasket; and

FIGURE 6 is a view in section taken on line 6-6 of FIGURE 1.

As illustrated in FIGURE '1, a typical. pumping unit includes an electric motor 10, a gasoline engine or the like, having a shaft 11 on which the impeller 12 of the pump is mounted. The impeller 12 operates in a scroll 13 having a centrally located inlet 14 communicating with the suction inlet 15 in the pump casing 16, which may be provided with a back flow check valve 17, although such a check valve is not required in many instances. The pump casing 16 is also provided with 'a discharge or pressure port illustrated as a threaded coupling; 18 by means of which the liquid drawn into the inlet passage is discharged from the pump. The check valve 17, when used, prevents back flow of liquid through the. inlet passage 15 and the coupling 19 secured therein so that a head of liquid is maintained in the pump for priming purposes.

The pump illustrated herein differs from prior pumps in the structure of the pump casing 16, the scroll 1 3- and associated parts. As shown in FIGURES 1 and 3, the pump casing includes a back plate 20 which may be-formed as a single casting having edge reinforcing flanges 2-1 and 22 and a hollow boss 23 in its mid portion for receiving thebearings and seals for'motor shaft 11 as will be explained more particularly hereinafter. The plate 20 has one fiat face 24 against which is secured the edge and peripheral flange 26 of a generally cup-shaped casing section 27 having slightly diverging-walls to enable easy removal from the mold. In making the casing section 27, the openings 28, 29 and 30may be formed therein for reception of the discharge coupling 18, the inlet or suction coupling 19 and a drain plug31. The openings are tapped to form threads therein mating with the couplings 18'and 19 and the plug 31.

Referring to FIGURES 2 and 3,. boththe back plate 20 and the casing section 27 are cast with aligned notches 32 and 33 for reception of fastening elements, such as the bolts 34, for securing them together in face-to-face relation with a sealing gasket 35 interposed between them and preferably spanning theentire surface of the plate 20. The notches 32and 33 do not requiredrilling or finishing.

The opposed portions of the'plate 20 and the casing section 27 may be surface finished on a flat grinder to the tolerances required to prevent! leakage therebetween. A plurality of the plates and casing. sections. canbe'ground simultaneously.

The pump scroll 12in the form; of theinvention shown comprises basically four parts, namely, a back wear plate 36, a front plate 37 having an inlet tube 38-and a pair of scroll blades 39 and 40asshown': in FIGURES l and 3.

The plate 20 is drilled by meansof a step drillto form a central stepped bore 41 in the boss 23 for reception of a shaft' seal and bearing 42 of conventional type through which the motor shaft 11 passes. Using the bore 41 asa cutting means, four holes 43 are drilled through the'boss 23 to receive screws 44 for securing the plate 20'to. the motor 10. In addition to the five holes mentioned'above, the Wear plate 36 is drilled to form blind holes or recesses receiving five positioning pins 45, 46, 47, 48 and 49: which are usedto position the wear plate 36, front plate 37, and blades 39 and 40 to form a scroll having a priming inlet 50at the bottom and a discharge 51 adjacent the top as shown in FIGURE 3.. If necessary,- small? bosses or detents 52' may be cast on the back of theplate20to pro'- vide additional depth to the blind holes receiving the locating pins 45 to 49:

The front plate 37 as shown in FIIGURE 4 is generally circular and has a flat lower edge 53 and the tubular extension 38 which extends forwardly into'contact with the inner flat surface 54 of the front of the casing'section 27 J or a gasket or flap valve member 55 to seal the tubular member around the suction inlet 15. The left hand face of the plate 37 is ground flat as are the front and back edges of the blades 39 and 40 to form a tight fit with each other to minimize leakage between the blades, the wear plate 36 and the front plate 37. Also, the plate 37 is drilled to form the blind holes or recesses 56, 57, '8, 59 and 60 for reception of the ends of the pins 45 to 49. Small dome-like bosses 61 may be cast on the front of the plate 37 to provide additional thickness for formation of the recesses 56 to 60.

As shown in FIGURE 5, the check valve 17 is a part of a rectangular gasket 55 of rubber or rubberized fabric having an arcuate slot 63 formed therein defining the flap valve 17 which as shown in FIGURE 1 is provided with stiffening weights 64 and 65 secured by means of a screw 66 passing through them and a central hole 67 in the valve 17. Elongated slots 68, 69, 70 and 71 are formed in the gasket 55 for reception of screws 72 to secure it to the inside of the casing section 27.

The impeller 12 may be of any suitable type such as a member having three vanes 73, 74 and 75 or more or fewer vanes of spiral form thereon and having a central opening 76 for reception of the reduced end portion 77 on the shaft 11 and a key 7-8 for securing them against rotation. The impeller 12 is also a casting and is drilled and ground to receive the shaft 11 and key 78 and is shaped to the proper diameter by grinding the tips of the blades thereon. A cap nut 79 retains the impeller on the shaft 11 in the proper relation to the wear plate 36. With the various elements of the pump described above, the pump is assembled by first securing the back plate to the motor housing by means of the screws 44. The gasket 35 is applied and the Wear plate 36 positioned in overlying relation to the gasket. The pins 45 to 49' are then inserted in the holes in the back plate 20 through corresponding holes (not shown) in the wear plate and the gasket and the blades 39 and 40 are assembled on the pins. The cutwater 80 of the blade 39 is used as a locating point for drilling the holes in the front and back plates so that the cutwater does not require machining or grinding. By locating the blades 39 and 4t) and the tips of the blades on the impeller 12 with respect to this common locating point, the positions of the locating pins 45 to 49 can be determined accurately. The impeller 12 is secured on the shaft 11 and the front plate 37 is assembled on and positioned by the free ends of the locating pins 45 to 49. The front casing section 27 with the flap valve gasket thereon is then secured in position by means of the bolts 34 which hold the entire pump in its assembled relationship.

By avoiding machining operations, and using relatively simple drilling and grinding equipment the manufacture of the pump is greatly simplified and its cost reduced. Moreover, the use of locating pins to establish the positions of the parts not only facilitates the assembly of the pump, but also makes very simple the disassembly of the pump for inspection and servicing as may be required.

As indicated above, the pump chosen for illustration is a self-priming pump. The casing, with or without the check valve 17, will retain sufiicient liquid therein that operation of the impeller will draw liquid up through the inlet 50, mix it with the air and discharge the froth so formed upwardly so that the air can be displaced and the liquid returned, thereby creating a reduced pressure in the scroll and enabling very quick and efiicient selfprim-ing of the pump. I

As indicated above, when the several parts of the pump casing and scroll are made by sand casting techniques,

some grinding and drilling are required for proper fit and to minimize leakage. Even the drilling and grinding operations can be eliminated by precision die casting of the parts so that only tapping of the holes 28, 29 and 30 is required to prepare the pump components for assembly.

It will be understood that the principles underlying the construction and assembly of the illustrative embodiment of the pump can be utilized in other pumps and, accordingly, the form of the invention described herein should be considered as illustrative and not as limiting the invention as defined in the following claims.

I claim:

1. A centrifugal pump comprising a back plate, a hollow casing section, means for securing said casing section to said back plate to form a pump casing, a wear plate adjacent to said back plate, a front plate spaced from said wear plate, a pair of curved scroll blades between said wear plate and front plate, a plurality of aligning pins extending transversely through said blades and said wear plate substantially perpendicular thereto, recesses in said back plate and said front plate for receiving the ends of said pins and securing said blades between said wear and front plates in the form of a spiral having an inlet adjacent the bottom thereof and an outlet adjacent the top thereof, means on said front plate and said casing section for holding said wear plate and said front plate in engagement with the edges of said scroll blades to form a pump scroll and an impeller in said scroll.

2. The pump set forth in claim 1 in which said means for securing said back plate to said casing section comprises a plurality of notches in the peripheries of said back plate and easing section and a plurality of threaded fasteners in said notches.

3. The pump set forth in claim 1 in which said casing section has an inlet opening in one side thereof and an outlet opening adjacent the top thereof and said means on said front plate and said casing section comprises an inlet tube extending from said front plat toward said casing section in alignment and in communication with said inlet opening and said scroll.

4. Acentrifugal pump comprising a pump casing including a back plate portion, and a detachable front section, a front plate in said pump casing, a pair of curved scroll blades between said back plate portion and said front plate, a plurality of locating and aligning pins extending transversely through said blades, recesses in said front plate and back plate portion for receiving the ends of said pins and securing said blades in the form of a spiral having a discharge outlet, means on said front plate and said front section for holding said front plate in engagement with an edge of each of said blades to form a spiral pumlp scroll and an impeller rotatably mounted in said scro '5. The pump set forth in claim 4 in which said back plate portion, front section and front plate are coreless castings.

6. The pump set forth in claim 4 in which said means on said front plate and said front section comprises an inlet tube on said front plate communicating with said scroll substantially coaxially of said impeller and extending toward said from section, said front section having an inlet port therein aligned and communicating with said tube.

7. The pump set forth in claim 6 in which one end of one of said scroll blades is spaced circumferentially of said scroll from one end of the other scroll blade at the bottom of said scroll forming a priming opening below said inlet tube and the opposite ends of said blades are in overlapping and radially spaced relation to dispose said discharge outlet upwardly and in communication with the interior of said pump casing above said inlet tube.

8. The pump 'set forth in claim 6 comprising a flap valve gasket interposed between the end of said inlet tube and said front section to prevent leakage therebetween.

9. The pump set forth in claim 6 comprising a wear plate interposed between said back plate portion and said scroll blades and said impeller, said pin-s extending through said wear plate and positioning it relative to said back plate portion.

(References on following page) References Cited by the Examiner UNITED STATES PATENTS Smith 103-11 Marlow 103-113 Blarcom 103-113 Hunter 103-113 6 FOREIGN PATENTS 660,725 4/1963 Canada. 459,801 1913 France. 848,810 9/ 1960 Great Britain.

MARK NEWMAN, Primary Examiner.

H. F. RADUAZO, Assistant Examiner. 

1. A CENTRIFUGAL PUMP COMPRISING A BACK PLATE, A HOLLOW CASING SECTION, MEANS FOR SECURING SAID CASING SECTION TO SAID BACK PLATE TO FORM A PUMP CASING, A WEAR PLATE ADJACENT TO SAID BACK PLATE, A FRONT PLATE SPACED FROM SAID WEAR PLATE, A PAIR OF CURVED SCROLL BLADES BETWEEN SAID WEAR PLATE AND FRONT PLATE, A PLURALITY OF ALIGNING PINS EXTENDING TRANSVERSELY THROUGH SAID BLADES AND SAID WEAR PLATE SUBSTANTIALLY PERPENDICULAR THERETO, RECESSES IN SAID BACK PLATE AND SAID FRONT PLATE FOR RECEIVING THE ENDS OF SAID PINS AND SECURING SAID BLADES BETWEEN SAID WEAR AND FRONT PLATES IN THE FORM OF A SPIRAL HAVING AN INLET ADJACENT THE BOTTOM THEREOF AND AN OUTLET ADJACENT THE TOP THEREOF, MEANS ON SAID FRONT PLATE AND SAID CASING SECTION FOR HOLDING SAID WEAR PLATE AND SAID FRONT PLATE IN ENGAGEMENT WITH THE EDGE OF SAID SCROLL 